1. Field of the Invention
This invention relates to an electrocardiograph, and more particularly to a portable electrocardiograph which enables a cardiopath to carry it with him or her and measure an electrocardiographic complex in case of unexpected heart attack.
2. Description of the Related Art
Since portable electrocardiographs are convenient for keeping track of the state of electrocardiographic waves in the cardiopath's everyday life, various types have been developed.
FIGS. 23 and 24 illustrate a conventional portable electrocardiographic-wave measuring apparatus. This electrocardiographic-wave measuring apparatus 100 has a case body 110 formed into the shape of a pencil. For portability, it can be put in and hung on a pocket with a clip 120 at one end of the case body 110. A first electrode 130 is provided on one end of the case body 110, and a second electrode 140 is provided on the surface of the middle portion of the case body 110. A press-button switch 150 is provided on the other end. Inside the case body 110, the electronic circuitry that measures electrocardiographic waves on the basis of the signals from the first and second electrodes 130 and 140 and a battery are housed.
FIG. 24 is an illustration to help explain how to use the electrocardiographic-wave measuring apparatus 100. Electrocardiographic waves are measured by pressing the first electrode 130 against the chest to the left side of the heart and pressing the switch 150, with the second electrode 140 on the surface of the body case 110 gripped with the right hand, for example. In this way, electrocardiographic waves can be measured whenever necessary.
However, the conventional electrocardiographic-wave measuring apparatus must have a relatively long body so that the user can hold it with his or her right hand and press the first electrode 130 against the chest. The conventional apparatus has another problem: depending on which part of the chest the first electrode 13 is pressed against and how the electrode is pressed against the chest, its contact resistance varies, and consequently the change in the contact resistance causes not only variations in the potential of the heart and noise, but also myoelectric noise attributable to muscular strain, preventing an accurate measurement of electrocardiographic waves. To solve this problem, as shown in FIG. 24, the electrocardiographic-wave measuring apparatus 100 must be pressed perpendicularly against the chest 170 to the left of the heart 170 at a suitable pressure. A shirt generally has buttons along its center line on the front, and therefore when something wrong has happened with his heart, the user must unbutton his shirt before pressing the electrocardiographic-wave measuring apparatus 100 against the chest 170 to the left side of his heart. In the case of clothes without buttons such as a pull-over sweater, the user has to take off the sweater, and therefore it takes him or her a lot of time to press the electrocardiographic-wave measuring apparatus 100 perpendicularly against the chest 170, preventing quick measurement. Especially for women, they may have to expose their chest in front of others for measurement and this will inflict mental pain on them.